Class 5 Lecture Demo

Class 5 Lecture Demo - The Raster Model

• Link to Class 4 Thematic US Census Mapping Submissions

• Link to Class 5 Agenda

• Demo Data Part I

• Demo Data Part II

Part I - Raster Model Exploration:

• Demo Data Part I

• Global Wind Atlas

  • Import Steps:

    • Add Raster Layer
    

    Add Raster

    

    Point Directly to Raster File

    

    Min > Max Values Displayed as Default

• Raster Properties - Symbolization:

  • Palleted/Unique Values = Discrete (Random Colors)
  • Singleband gray
  • Singleband pseudocolor -
    • Three types of color interpolation are available:
      • Discrete
      • Linear
      • Exact
    • Classification Methods:
      • Continuous
      • Equal Interval
      • Quantile

Raster Classed as Equal Interval

• Histogram:

Histogram for Raster Values

Part II - Assignment Overview (Map #1)

• Demo Data Part II

Demo Data Part II

• Step 1 - overlay Zimbabwe Admin Level 1 to the population raster data:

Admin Level 1

Symbolized Layers

• Step 2 - enact Zonal Statistics:

Apply Zonal Statistics

• Step 3 - utilize Field Calculator to derive square area in kilometers:

Run Areal Calculation

• Step 4 - utilize population density formula from Assignment 4 to generate population density as ppl per sq. km:

Density Formula

• Table Result:

Sum > Sq. Area > Pop Density

Further Reference:

• Color Ramps for QGIS, both vector and raster
• creating continuous color ramp in QGIS layout
• QGIS Raster Symbology